This is also the only SR/TJ convert DVD with 24bit PCM audio.
Then there's the Blu-Ray version of Ultra C, with exactly the same audio template as Zazen.

And of course, the venue probably makes a difference too. Maybe they figured Ultra C wouldn't have any audible improvements from the audio being packaged beyond 2304kbps. They could have more than doubled that, without compromising the video quality.

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You know Tokyo Jihen is a supergroup, when you can't blame most of the members for wanting to pursue other projects.